What metaphors are used in Blood of the Fold by Terry Goodkind?

A dacra is a metaphor for transfer of energy. A dacra is a dagger that is used by the Sisters of the Light. A dacra can take the magic out of a person after it punctures their skin. The dacra doesn't have to be somewhere vital. It is a dacra that Millie slips to Verna while she is in the cell accused of being a Sister of the Dark.